I have a standard gas boiler heating the hot water and radiators. The
hot water cylinder has an indirect coil.

There's a cold water tank and a seperate header tank for the rads/coil
in the loft. The base of the two tanks is level, so the water in the
header tank is a couple of feet below the main tank.

I've been suffering problems with the overflow from the header tank
dripping. So I changed the rubber washer. Then the fibre washer. Then
I turned off the stop cock. Now I've actually disconnected the feed
into the ball valve from the tank - and *STILL* it drips. The only
thing I can think of left that could be causing the problem is a leak in
the coil in the cylinder. Before I go out and spend 200 squid on a new
tank and spend a weekend pulling the darn thing apart, is there anything
easier/cheaper that could be causing it?

Ta

Andy